XV is a little closer to home for Nomura than KH is, so I wonder what issues he'd care about.
A main subject is bonds, that is, relationships. I imagine that character interaction will be a significant factor. Whereas XIII is more about the lore and the world (that, unfortunately, we don't really get to explore, at least, for most of the game), XV seems to be more about the people. That isn't to say the FNC mythology will not play a big role, but I don't think it will take precedent over the characters.